General Anesthesia, Utilizing Etorphine Hydrochloride and Azaperone with Supplementary Isoflurane Inhalation Anesthesia, for Gastro-esophageal Endoscopy in a Domesticated Asian Elephant (Elephas maximus): A case report

Abstract

A 30-year-old female domestic Asian elephant (Elephas maximus) was referred to Kasetsart University Veterinary Teaching Hospital for investigation of an esophageal obstruction. “Vomiting” had been noted for several days before admission. Initial sedation was achieved by azaperone (80 mg), delivered intramuscularly (IM). Once sedated supporting straps and a sling were fitted, and weight-bearing support was provided by a crane. General anesthesia was induced using 2 mg etorphine hydrochloride (0.00066 mg/kg) by intravenous (IV) injection. Using the crane, she was lowered onto a thickly bedded area on the floor and placed in right lateral recumbency. Oxygen was initially provided via the trunk. Blind endotracheal intubation was unsuccessful until further two incremental doses of etorphine hydrochloride (0.5 and 1.5 mg) had been administered. Even though subsequently maintained on 5% isoflurane, a third increment of etorphine hydrochloride (1 mg) was required to fully abolish jaw tone. Following successful endoscopy for gastro-esophageal evaluation anesthesia was reversed through cessation of isoflurane and administration of naltrexone (500 mg by IM injection). Some reflexes including ear twitching and leg moving were noticed within 1 min and endotracheal extubation was carried out after 2 min, when jaw tone returned. First attempts at standing took place after 3 min, the elephant could stand with support after 8 min and was ambulatory at 11 min after reversal. The total time from sedation to independent walking was 1.16 hr.